Most often during games, Penn State coach James Franklin is too busy preparing for the next play to focus very long on the last one. But several times Saturday night, after yet another jaw-dropping Saquon Barkley run against Iowa, Penn State’s coach caught himself turning to the players nearest him on the sideline with an expression of, are you kidding me right now?

“The reactions on their faces are kind of funny,” Franklin told the All-American on Sunday, a day after his star running back’s transcendent performance in the Nittany Lions’ last-second 21-19 road win. “I’m like — do you realize what you’re seeing?

“I want to say to them, I hope you appreciate what’s happening. You’re 18-and-a-half years old. Some people go a lifetime without seeing something like this.”

Barkley, who finished with 358 all-purpose yards, a touchdown and one gravity-defying hurdle, has been breaking defenders’ ankles for two-plus seasons. He broke a...